1. Technical Field
This disclosure relates to a method of removing edges on the end of an eyeless operating needle blank and, more particularly, to using a laser to remove the edges on the proximal end of eyeless surgical needle blanks.
2. Background of the Related Art
An eyeless operating needle blank has a proximal end portion with a bore formed therein of a predetermined depth extending along the axis of the needle blank. An end of a suture is inserted into the bore and, subsequently, the end portion is staked, to attach the suture to the needle blank. Opposite the proximal end portion is a distal tip portion for piercing soft tissue.
Many techniques exist for forming the bore in the end portion of the needle blank, such as, drilling machine, electric discharge machining, electron beam machining, laser beam machining, etc. These machining processes may leave nonconformities at the inside and outside diameters of the bore. In needle blanks with small outside diameters the wall of the needle blank defined between the bore and the outside diameter is very thin and can be very sharp. The sharp edges on the inside diameter of the needle blank can cause the suture to rupture and break away from the needle blank prematurely, i.e., when the needle blank is bent relative to the suture. Sharp edges or burrs on the end of the needle blank can also be created on the outside diameter during manufacture (i.e., cutting the needle blanks to length). These sharp edges or burrs result in rejection during the needle blank inspection process.
Sharp edges or burrs can be eliminated by breaking the edges on the inside and outside diameters at the entrance of the bore. Heim, U.S. Pat. No. 4,159,686, teaches a method for smoothing the eye of a needle blank. The method includes using a laser beam to round out edges, however the techniques disclosed are for use in sewing needle blanks which define an eye substantially perpendicular to the needle blank's axis. Wendell, U.S. Pat. No. 5,344,412, teaches laser machining for catheters. The catheters have side ports laser machined substantially perpendicular to the longitudinal axis of the catheter.
U.S. Pat. Nos. 5,371,338 to Proto and Buchter, 5,384,945 to Spingler, 5,453,595 to Proto and Buchter and 5,479,980 to Proto, all incorporated herein by reference, disclose devices for creating needle blanks and drilling bores into the ends of the needle blanks. Wire from a spool is tensioned, cleaned and straightened. The wire is manipulated and aligned along its longitudinal axis with a laser beam. The distance from the laser beam and the alignment of the work piece with respect to the laser are precisely arranged. The laser drills a hole into the end portion of the wire and the wire is cut to length to create a needle blank with a bore for a suture. The bore is created by a laser beam aligned with the needle blank along its longitudinal axis. It would be advantageous to introduce an edge removing technique after the operation of drilling the bore. The prior art teaches that laser machining be done at an angle with the longitudinal axis of the needle blank. This would require realignment and refocus of the laser beam if longitudinal alignment is required to drill the bore. This would be time consuming and difficult to incorporate into the process.
Therefore, a need exists for incorporating a laser process which can provide a rounded edge to both the inside and outside diameters of the suture end of an eyeless needle blank. It would be advantageous to be able to maintain the laser beam along the longitudinal axis of the needle blank in order to round out the edges of the bore. It is also desirable to be able to use the drilling laser for creating both the bore and for rounding its edges.